Falsely inflated #s for the F30
42% increase in sales over November 2011 is because the e90 was on its last legs and who would buy an e90 with the f30 coming out in a couple of months.
Better number to look at is the 2011 vs 2012 YTD #s. 3.5% increase and you introduced a brand new model? F30s aren't selling too hot for a new model.
In contrast, for the year 2006 (first year of e90), BMW sold 17% more 3 series world wide compared to 2005. I wasn't able to pull up US sales numbers, nor see a breakdown between coupe/sedan, but regardless 17% is a much higher number than 3.5%.
You can attribute several factors such as the stagnant global economy in 2012 vs. the boom year of 2006. Bottom line, F30s are not selling well enough to the point that BMW right now is offering $1,000 Holiday Cash for a brand new model 3 series.